Circuit controller



Nov. 5, 1935. N. c lscHELLENG'I-:R 2,019,993

CIRCUIT CONTROLLER original Filed Feb, 25, 1931 2 `sheets-sheet 1 Nov. 5; 1935. yN. c. SCHELLENGER 2,019,998

CIRCUIT CONTROLLER l Original Filed Feb. 25. 1931 2. Sheets-Sheet 2 Patented Nov. 5,1935

CIRCUIT CONTROLLER Newton C. scheuenger, Elkhart, 1nd., assignor to Chicago Telephone Supply Company, Elkhart, Ind., a corporation of Indiana Original application February 25, 1931, Serial No.

Divided and this application March 30, 1932, Serial No; 602,007

15 Claims.

This inventionrelates to circuit controllers, and more particularly to circuit controllers for use in volume control units for radio equipment and the like.

5 In the preferred embodiment of my invention I have disclosed a circuit controller comprising a Wound wire resistance concentrically mounted in 'a suitable casing, and adapted to be engaged by a suitable contact or shoe carried by a rotat- .0 able actuating arm.

As discussed more fully in my eopending application Serial No. 518,281, filed February 25, 1931, this application being a division`thereof, the controller of the present invention possesses distinct advantages over those of the prior art. While I have provided a wound wire resistance, it is to be understood that any other suitable resistance may be used, and the invention is not to be limited to controllers having only wound l wire types of resistances.

One feature of the present invention resides in the compact assembly of the resistance within the casing. The resistance is formed by winding a wire upon a substantially elongated rectangular 25 strip of insulating material, whichmay be fiber,

or a combination of fiber and a phenolic compound, the strip preferably being laminated. The resistance is then formed into a substantially cylindrical configuration, and is provided with ter- 80 minal members secured over and short circuited on the end turns of the coil. These terminal members are extended outwardly through suitable openings formed in the cup-shaped casing and the resistance coil is mounted within the 85 casing with its ends in abutting engagement.

In connection with this feature, the contact strip is held in place within the casing by expanding it into the shell and utilizing its compressive strength for maintaining it in substan- 40 tially cylindrical` form and concentric position about the rotatable rheostat shaft.

Also, the manner -of bringing the terminals out from the interior of the shell without providing an opening through which'dust or foreign matter might enter the interior of the shell, assures that the resistance strip will be disposed within the shell in substantially a dust-proof casing. Associated with this feature is the novel manner of making electrical contact between the terminals andthe Wire resistor.

' Another feature of the present invention is the provision of a dust-proof casing, a part of which may be in the form of a cover or a cooperating shell engaging the cup-shaped shell, and completely enclosing the operating parts of the controller. l

Numerous other advantages, such as the manner of assembly and the construction of individual parts of the controller, will be more apparent 5 from the following detailed description, which, taken in connection with the accompanying drawings, will disclose to those skilled in the art the particular 'construction and operation of a preferred embodiment of the circuit controllery of the present invention.

In the drawings:

Figure 1 is an elevationalview of the controller as assembled; I

Figure 2 is a sectional view taken substantially l5 on the line 2 2 of Figure 1, showing the interior of the controller shell, the controller being provided with a knob for actuating the same;

Figure 3 is an end elevational view of the controller with the cover removed; Figures 4 and 5 are fragmentary detail views of the contacting means and the terminal members of the controller, showing the contacting shoe in two positions relative to the terminal end of the resistance strip;

Figure 6 is a fragmentary sectional view taken substantially on the line 6 6 of Figure 3;

Figure 7 is a partial sectional view, taken substantially on the line 1 1 of Figure 3;

Figure 8 is a perspective detail View of the 30 center terminal of the controller; and

Figure 9 is a perspective detail view of one of the terminals connected to each end of the resistance strip, and

Figure 10 is a fragmentary, sectional view of 35 a detail.

Referring now in more detail to the drawings, and particularly to Figures 1 and 2, I have disclosed a cylindrical cup-shaped shell member I forming part of a. closed housing. The shelly has a cylindrical wall 2 and a substantially at end wall 3. The end wall 3 has a bearing sleeve 4, Which may be formed of brass, bronze or the like, and which is secured in an opening formed in the end wall 3 of the shell member. 45

The sleeve is substantially concentric with the cylindrical wall 2 of the shell or casing I, and serves as a bearing for the actuator shaft 5, and also serves to support the rheostat or controller on a panel 6, which may be a thin metallic plate or the like. The outwardly projecting portion of the sleeve 4 is threaded as shown at 1, and receives a clamping nut 8 for securing the controller to the panel 6, there being a washer 9 interposed between the nut and the panel.

The opening in the end wall 3 of the shell member preferably is provided with radial projections, and the sleeve is expanded into engagement therewith by endwise pressure upon the shoulder III. A suitable knob or actuating member I2, formed of bakelite or the like, is secured by means of a setscrew I3 to the outer end of the shaft 5,

the shaft, as by means of the riveted head I8' thereof, which may be spun over or suitably formed to hold the actuator arm I6 in firm nonrotative engagement therewith. 'I'he hole in the actuator I6 is provided with keying projections y,

extending radially inwardly, and when thereduced end of the shaft 5 is riveted thereover, the

metal is expanded into keying engagement withv these projections. The actuator is thus held between the shoulder of the shaft and the riveted head in non-rotative engagement. The arm or actuator I6 also serves to lixnitendwise movement of the shaft outwardly of the casing, thus cooperating with the split ring I4 for holding `the shaft in operative position within the casing.

The housing or shell member I contains a cylindrical resistor I9, which comprises, in a pre.- ferred embodiment, a strip of laminated phenolic compound I9 of a special composition rendering the same suiliciently flexible to permit bending, whenheated, of the relatively short length which is thus formed into cylindrical shape. A resistance wire, preferably of great length and of very small diameter is wound upon the strip I9. For example, the strip I9 may be wound with wire .002 ci an inch in diameter with but .0001 of an inch space between the turns thereof. Such a resistor will thus have 499 turns of wire per. lineal inch along the strip, providing a very ilne adjustment of resistance for the controller. The particular diameter of the wire, and the number of turns per inch, is, o1' course optional. The ends of the strip I9 are notched, as shown. at 20 in Figure 2, to permit the passage of a rivet 22 therethrough, as will be described in detail later.

Between the resistor I9 and the hanged wall 2 of the shell is inserted an insulating strip of ber 23, which, after suitably dehydrating, is cut to a length such that it ts snugly into the interior 0f the cylindrical wall when the ends are brought into registry by expanding vthe same under pressure within the shell or housing. As shown in Figure 3, the abutting ends of the insulating strip 23 are indicated at 24, and are disposed diametrically opposite the abutting ends, indicated at 25, of the resistance strip I9.

'I'he liner 23 is provided with openings having the form of slit's, such as the slit 29 shown in n Figure 6, andthe shell is provided with a pair of openings or apertures 21 which are disposed at each side of the abutting ends 25' of vthe resistor. 'I'he slits 26 of the liner 23 are so disposed as to register with the central parts of the apertures 21, and through these slits and apertures are thrust the lead portions or terminals 28 of the terminal members 29. The terminal members 29 are formed of springy sheet metal with a. base or foot portion 30 extending at substantially right angles to the terminal or lead portion 28.4 'I'his base portion 30 is cu-t or notched-at 32 to provide clearance around the rivet 22, which rivet is grounded on the shell I, as 'shown in Figure 7. At the juncture of the base 30 and the terminal 5 portion 28 of the terminals 29 I provide a corrugation or webv 33 to strengthen the connection between the terminal portion and the base 'portion. This inhibits breakage by bending at the corner. 10

These terminal portions being thin iiat members project through the slits 26 to the exterior of the housing. The liner 23 forms a shield for the openings -21 as the slits grip thelead portion 29 closely, preventing the entry of foreign matter 15 such as dust, dirt and the like to the interior of the` controller. The members 29 are made as left hand members and right hand members, as will be apparent from Figures 3 and 7, but otherwise' are identical in form. The terminal por- 20 tions 28 thereof are adapted to receive connecting wires, and for thispurpose are provided with eyes or openings 34 at their outer ends, and also have dove-tailed notches 35 adjacent the eyes or openings 34. The dove-tailed notches 35 pro- 25 vide a portion of reduced diameter around which still other wires may be connected and thereby held preparatory to being soldered to the terminal 28. The shape of the corners of the dovetailed `notches tends to catch the turns of Wire 30 and hold the same securely. v

A ring or washer 36 of insulation such as ber, or the like, is disposed between the end Wall 3 of the cup I and the resistor I 8, as shown in Figures 2, 6, and '7. In assembling the parts Within the 35 cup or shell member I, the washer 36 is rst introduced inside the cup, then the liner 23, which has been dehydrated to shrink the same, is introduced into the cup and the opening 31 at the central part of the liner is brought into register 40 with an opening in the cylindrical wall 2 as shown in Figure 2, and the liner is then expanded until its abutting ends are aligned as shown at 24 in Figure 3. Thereupon the terminal members 29 and leads 28 are thrust through the slits 26 -in 45 the liner and the bases, which are lefts and rights, have their notches 32 extended toward each other and rest against the inner cylindrical wall of the liner. The resistor, which is coiled up in cylindrical form, is then introduced into the shell and itis expanded with considerable force until then ends which are alined with the opening 31 in the liner and the opening in the shell I, abut into abutting relation. 'I'he round notches 29 then provide an opening through which the shank of the rivet 22 extends. k

It will be observed that the base portions 30 of the terminal members '29 (see Fig. 9) are ilat and not cylindrical. Therefore, when a' resistor is expanded to bring the ends into register it is rst necessary to spring the ilat bases 30 into the form of arcs so that the base portions 30 conform t0 the curvature of the liner 23 and the resiliency of these parts causes them always to thrust inwardly against the resistor, and particularly against the turns of the winding at the` aoiaeea it is desired to short circuit a portin``of the beyond the terminal.. This is especially truein rheostats or circuit controllers having a switch in combination therewith, as disclosed in my copending application, .Serial No. 602,006, filed March 30, 1932, so that enough o! the-winding is short'circuited to providezerofresistance -after the switch closes the circuit. 'I'he rivet 22 has ya cylindrical shank which extends through the .alined openings of the resistor, the insulating strip. and the cylindrical shell member; Obviously, the shank of the rivet --31 might betapered adjacent the head 33'- for r frtherexerting a spreading force upon the ends of the resistor strip I9 as shown in Fig. 10. The

rivet has a spring washer 3B `under the head 3l. for .fspreading' the pressure of the rivet, this washer being sprung into an arcuate form when the rivet is drawn' up. The abutting ends of the resistorsupporting strip I9, Figures 2 to '5,'in-P clusive, are thereby held in register both radially and axially. A central or grounded terminal 4l' is clamped to the outside of the center cylindricalwall by the. beaded or riveted end of the "rivet 22. "The terminalmember 40, as shown in' detail in Figure 8,",has a terminal portion 42 subt stantiallylike the portion 28 of the terminal member 29. base or body'portion 43 has a hole 44j therethroughwhich receives the rivet 22,

. and is provided with-la small projection 45 entering a opening. 46 in the cover member, as. s h'ow'n in vFigure 1, to secure the" member rotation about the axis of the rivet eo thet the1 termina1 portions n, n and a: all'in the same plane, as is ap parent viromli'igure 1'. The end of the casing is closed by la. nietallic cap 41 which has a ange embracing the. outside of the cylindrical wall 2.

The outer edge of the cylindrical wall 2 is rounded on both inside andl outside corners to facilitate, the application of the cap to the outside thereof, and also tofacilitate the insertion of the liner 23 on theinside of the shell. This rounded edge also prevents the cutting of the wire windings carried by; the strip I3 during assembiy .thereof witmnith'e `shell, which might oel cur if the inner edge `oi'wall 2 were not rounded.

The actuator or" arm I6 is provided with two hooks or projections 48 spaced apart angularly with tothe axis of the shaft by a relatively 'wide angle. The actuator IB carries the member 49, thisshoe member having a pair of runners SII, which are formed integrally of a piece of thin sheet metal, preferably of a special composition for insuring good-contact with the resistance wire. The particular formation of the contactor shoe is described more in detail in my abovel mentioned copending application, Serial No. 518,281, led February 25, 1931, of which application the instant application is a division. Sumce to say that the shoe 49 is provided with yoke-shaped ends I which engage about thehooks 48 for securing the shoe to the actuator Twostop'arms 54 oneachsideofthespring member 52 and integral with the actuator arm I! are adapted to engage thehead 38 of the rivet 22 for limiting the motion of the arm, and consequently limiting the motion-of the contactor 5 shoe. These stop arms or projecting lug portions extend through the yokes of the shoe 49, and the shoe is freeto have universal movement thereabout. I'he arm I6 is also provided with 'an extending tongue portion 55 having an opening y56 10 therein, this opening being adapted to receive an operating pin when the circuit controller is mounted in conjunction with the circuit opening and closing switch. The arm I6 is also provided with a pair of diametrically extending slotted 16 tongues 51, which are adapted to receive a coupling member when two or more circuit control- 1ers are mounted in tandem arrangement, as fully described in my above mentioned copending ap- ,plication.` v

'Jf 'I'o insure smooth operation mechanically and electrically-within the circuit controller, the

housing lisicompletely closed to exclude dust and foreign particles, and in addition the resistor strip and theliner and all insulating parts within the shellare covered with a neutral oil which forms a lm upon the metallic contacting parts.

`The oil lm also surrounds the insulating strip After the rheostat is assembled the ber liner is permitted to resume its normal moisture content, whereupon it expands and grips the resistor rmly. The oil is then introduced for the purposes above described.

While I have shown the terminals such as 28, extendingout through the cylindrical wall 2, it is to be v'understood that I do not wish to limit the' invention to that manner of taking out the 46 terminals. A ber' end liner or washer similar to washer 36 may be disposed withinthe open end of the shell and the terminal portions may be extended through corresponding slits in such washer and corresponding slots or apertures in thecap or cover member 41. 0r, if the mountin g permits, the taking out of the terminals may ings or apertures through which the terminals 55 are projected isadvantageous in preserving a complete closure. The soaking of the ber insulation in oil assists, also, in excluding foreign particles such as dust and the like. Ihe shaft 5 ts in the sleeve 4 with a very close t and the 50 dimensions are heid relatively close for end play, s0 that there is practically no opportunity for foreign particles to enter along the shaft.

The resistor I B may be made up in a variety of fcnns and to secure various effects, as above pointed out, without departing from the scope of the present invention. I have described this ristor as comprising a very large number of turns oi' ne wire wound about the strip of in= 70 sulation I9. Preferably bare wire is employed, as with im' method cf making contact. bare wire with very little space between turns is entirely' feasible, and there is not the diiculty oi' removi ing the enamel or other. insulation which is the ing applied after the winding of the wire upon' the strip and upon setting, or hardening, it forms a definite tie between the central parts of the coils and the side of the strip, which serves to anchrr the turns against any shifting by the contactor. The bending of the stripv does not cause the cement to crack or split from between the adjacent coils.

The wire may be wound upon a smooth edgedv strip I9. Normally I prepare the stripl9 before Winding by carefully rounding the edges and truing "the edges so as to assist ini the accurate placing of the individual turns of the lwire. It is desirable to cause the wire to be placed accuratelyand uniformly.

'Ihe wire which is wound upon the strip does not need to be the same throughout; there may be different sizes of wire wound upon thesame st rip, as, for example, the resistance strip may be wound with relatively coarse wire at a relatively coarse pitch adjacent the zero side Of/the' resistance, and may be changed into relatively fine wire with a relatively fine pitch as Athe resistance nears the opposite end of the strip.

Other obvious changes may be made in the details of my circuit controller without departing from the scope and spirit of the invention, and I 'do `not intend to be limited to the exactem-4 bodiment shown and described, but only in ,so far as defined by the appended claims.

l. In combination, a. substantially cylindrical cup member forming a housing, the cup member having openings through the cylindrical wall, a liner of insulation closely tting the inner cylindrical wall of the cup member, said liner having openings in alinement with the openings in the shell, terminal members having flat base portions and thin outwardly extending lead .portions, the lead portionsbeing thrust through said openings, a cylindrical resistor comprising a fiat strip of insulation having a wire winding thereon brought to cylindrical form with' the ends thereof abutting under compression, the ends of the wire winding engaging the base portions of the terminal members to secure electrical contact therewith.

2. In combination, a substantially cylindrical cup memberform'ng a housing, the cup member having openings through the cylindrical wall, a liner of insulation closely tting the inner lcylindrical wall of the cup member, said liner having openings in alinement with the openings in the shell, terminal members having flat base portions and thin outwardly extending lead portions, the lead portions Ybeing thrust through said openings, a cylindrical resistor comprising a flat strip of insulation having a wire Winding thereon brought to cylindrical form with the ends thereof abutting under compression,I the ends of the w'lre winding engaging the base portions of the terminal members to secure electrical contact therewith, and pads of soitv metal disposed between the foot portions of the terminal members and the winding to form extensivevcontact between the winding and the ter-A minal members.

3. In a device of the class described, a metallic housing .comprising a cylindrical cup member )having a bearing sleeve coaxial with the cylindri cal wall thereof, a liner of insulation closely fitting the interior of the cup member, said cup member having openings through a wall thereof, terminal members of sheet metal comprising base portions and outwardly extending lead portions,

said liner having openings in alinement with the openings in the cup member and the lead' portions being thrust through said liner. openings, a resistor comprising a flat strip of insulation having a resistance wire coiled thereupon to l points adjacent the ends of the strip, the ends of the strip being brought into abutting relation under compression between said terminal members, the base portions of the terminal members being brought -into electrical contact with the 2 ends of the resistance winding by the radial outward thrust of the strip, and a pin extending through the strip at the ends thereof and through the cup member, said pin having a head for holding the abutting ends of the strip in alinement. 2

4. 'I'he method of mounting a resistor in a shell which comprises fo g a cylindrical cupshaped shell, disposing a compressible lining strip of insulation on the cylindricalinside surface of the shell, forming a wire wound strip of insulation 3 to a length slightly in excess of the inner periphery of the lining, disposing the strip within the lining, and extending the strip to bring the abutting ends thereof into register'under coms pression.

5. In combination, a shell having a cylindrical wall, a liner of insulating ber on the inside of 'the cylindrical wall, a resistor comprising a wire.

wound strip of insulation, and terminals having inserts disposed'on the inner wall of the fiber liner and extending from said projecting portions circumferentially of said shell between said liner and said resistor, said resistor being of a portions projecting from said shell and at metal 4 length slightly greater than the normal internal 4 perimeter of the liner so that when the ends thereof are brought into abutting engagement a relatively great outward radial thrust will Vbe created holding the resistor in the shell and providing permanent contact between thewinding 5 and the metal inserts.

6. In combination, a housing having a cylindrical wall, openings in the wall, a liner of insulating material inside of the cylindrical wall,

said liner having openings ,in register with the 5 said terminal members having at leads extending through the openings in the liner, and a headed pin extending through the registering notches of the resistor, through the liner and through th'e housing, -the head of the pin holding the abutting ends of the resistor in alinement.

7. The combination with a housing having a cylindrical wall, a liner therein, the cylindrical wall and the liner having alined openings, of a terminal member having a thin base portion dis,- 71

Aexpanded into substantially cylindrical form with the ends thereof abutting in alinement under compression, and a headed pin extending through the liner and the cylindrical wall for holding said abutting ends in alinement.

8. In combination, a cylindrical shell member having a pair of apertures therein, a liner of insulation on the cylindrical wall thereof, said liner having apertures in register with the apertures in said shell member, registering openings in the liner and in the shell between said apertures, terminal members having thin base portions disposed on the inner wall of the liner and having flat leads projecting through the apertures, said base portions having notches adjacent the registering openings, a resistor strip expanded into engagement with they liner and having its ends abutting to hold the same under compression, said abutting ends being alined with said registering openings, and a headed pin extending through the alined ends and through the registering openings for holding the said ends in alinement and pressing. the ends of the wire winding into engagement with the base portions of the terminal members.

9. In combination, a metallic supporting member, an insulating member in contact with the surface thereof, a terminal member having a flat base portion disposed upon said insulating member, a resistor comprising a strip of insulation having a wire winding thereiponextending to a point adjacent the end thereof overlying the insulating member, the base portion of the terminal'member lying between the resistor and the` insulating member and in contact with the end of the Wire winding, and a rivet extending through the end of the strip of insulation, the

insulating member and the metallic supporting i member, said base member being formed to provide clearance between itself and the rivet.

10. In combination, a closed metallic housing having openings large enough to permit terminals to extend therethrough with clearance to avoid contact, a cylindrical wire wound resistor in the housing, a lining of insulation between the resistor and the adjacent walls of the housing, a shaft journaled in a wall of the housing substantially concentrically with the resistor, a movable contact shoe Afor engaging the windings of the resistor, said shaft having an actuating arm for the' shoe,'terminals projecting through the lining and the openings, said lining serving as a seal between the openings in the. housing and the terminals, said terminals having contacting portions within the housing connected with the windings of the resistor.

l1. In combination, a closed metallic housing hav g openings large enough to permit terminals to e tend therethrough with vclearance to avoid contact, a cylindrical wire wound resistor in the housing, a lining of insulation between the resistor and the adjacent walls of the housing, a

shaft journaled in a wall of the housing substantially concentrlcallywith the resistor, a movable contact shoe for engaging the windings of the resistor, said shaft having an actuating arm for the sh, terminals projecting through the lining and the openings, said lining serving as a seal between the openings in the housing and the terminals, said terminals having contacting portions within the housing connected with the windings of the resistor, said housing containing a body of lubricant for lubricating the shoe and the resistor.

l2. In a rheostat, a housing, a cylindrical insulating liner engaging the inner surface of said housing, a concentric resistance strip spaced from said housing by said insulating liner, said resistance strip having notched abutting ends, and means including a tapered conducting member extending through said housing for expanding said abutting ends to position said strip in said housing.

13. In combination, a metallic rheostat housing having openings large enough to permit terminals to extend therethrough with clearance to avoid contact, a resistance element positioned adjacent the inner wall of said housing, a ilat lining of insulation, means securing said insulation in fixed position between the inner wall of the housing and said resistance element, terminals projecting through the lining and the openings, said lining fltting closely around said ter.- m nals to serve as a positioning means for the terminals and the sole means of insulation between the edges of the housing surrounding the openings and the terminals.

14. In combination, a metallic rheostat housing .having openings large enough to permit terminals to extend therethrough with clearance to avoid contact, a resistance element positioned adjacent the inner wall of said housing, a strip of insulation between the wall of the housing and said resistance element, means xedly securing said strip in said housing, said strip having openings therethrough smaller than the metallic housing openings, terminals projecting through the strip openings and the housing openings, said strip serving as a positioning means for the terminals to prevent electrical contact with the housing. i

15. In a circuit controller, in combination, a metallic housing member having an opening therein, an insulating member lying against the inner wall of said housing member and having an opening registering with the opening in said housing member, a resistance element disposed Cil against said insulating member, a terminal having a substantially at contact portion interposed between said resistance element and said insu-` llating member and a lead portion extending 

